How Does Egg Freezing Work? Steps, Timeline, and What to Expect

What is the overall timeline?

An egg freezing cycle typically spans 10–14 days of stimulation, with the retrieval procedure at the end. Here is how each phase unfolds:

1. Consultation and baseline evaluation — bloodwork (including FSH, AMH, and estradiol) and an ultrasound to count antral follicles. This tells your clinician how your ovaries are likely to respond to stimulation 2Ref 2Practice Committee of the American Society for Reproductive Medicine (2021).Fertility evaluation of infertile women: a committee opinion.Baseline fertility evaluation including ovarian reserve assessment (AMH, AFC, FSH) that informs candidacy and expected response before egg freezing. 2. Suppression (sometimes) — some protocols start with birth control pills or a GnRH agonist (such as leuprolide) to synchronize the follicles before stimulation begins. 3. Stimulation — you inject hormones (FSH and sometimes LH) once or twice daily, usually in the evening, for 10–14 days. These prompt multiple follicles to grow simultaneously. 4. Monitoring — frequent clinic visits (every two to three days) for blood draws and vaginal ultrasounds to track follicle development and adjust the medication dose. 5. Trigger shot — once the leading follicles reach the target size, a final injection (hCG or a GnRH agonist) is given to complete egg maturation. The retrieval is scheduled exactly 35–36 hours later. 6. Egg retrieval — a 20–30 minute outpatient procedure done under sedation. A thin needle is guided by ultrasound through the vaginal wall into each follicle to aspirate the fluid containing the egg. 7. Vitrification — mature eggs are identified in the laboratory and immediately flash-frozen using vitrification, which prevents ice crystals from forming and is now the standard protocol at most centers 3Ref 3Practice Committee of the American Society for Reproductive Medicine (2021).A review of best practices of rapid-cooling vitrification for oocytes and embryos: a committee opinion.Vitrification as the standard rapid-cooling protocol for oocyte cryopreservation; key performance indicators including post-warming oocyte survival. Eggs are stored in liquid nitrogen.

What do the injections feel like?

The injections use small needles similar to an insulin pen and are typically given in the abdomen or thigh. Most people learn to self-inject after a nurse demonstration. The injections themselves are brief; the most common discomfort is mild bruising at the injection site.

During stimulation, the ovaries enlarge as follicles develop. It is common to feel pelvic fullness, bloating, or mild pelvic discomfort — especially in the last few days before retrieval. Heavy exercise and activities that involve twisting or impact are generally discouraged during this phase because enlarged ovaries are more susceptible to torsion.

What happens during and after the retrieval?

The retrieval is done in the clinic's procedure room, usually under intravenous sedation so you are comfortable and unaware of the process. You will need someone to drive you home afterward.

After the retrieval: - Cramping, similar to menstrual cramps, is common for one to three days - Spotting is normal - Most people return to work within one to two days - Your period will arrive within a week to two weeks, after which the ovaries return to their baseline size

The embryology lab will notify you of how many mature eggs were retrieved and successfully vitrified. Not every egg retrieved will be mature, and not every mature egg survives vitrification perfectly — this is expected and factored into the planning.

How many eggs do I need?

There is no single number that guarantees a future pregnancy, because the egg-to-live-birth rate depends on the age at which the eggs were frozen, individual egg quality, and what happens when the eggs are thawed and fertilized in the future. Available evidence suggests outcomes are more favorable when eggs are frozen at younger ages 1Ref 1Practice Committees of the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology (2013).Mature oocyte cryopreservation: a guideline.Removal of the 'experimental' label from oocyte cryopreservation (2012); evidence that fertilization and pregnancy rates are similar to IVF with fresh oocytes when vitrified eggs are used.

Your reproductive endocrinologist can give you an estimate based on your ovarian reserve testing and age. Some people do more than one cycle to reach a target number of eggs. It is worth understanding that frozen eggs are a resource — not a guarantee. The goal of freezing is to have more options in the future, not to eliminate uncertainty entirely.

Who is egg freezing for?

Medical fertility preservation: People facing chemotherapy, radiation to the pelvis, or surgery that might affect ovarian function often freeze eggs as part of an oncofertility plan 4Ref 4Su HI, Lacchetti C, Letourneau J, Partridge AH, et al. (2025).Fertility Preservation in People With Cancer: ASCO Guideline Update.Recommendation to offer fertility preservation (including egg freezing) to patients with cancer before gonadotoxic treatment begins. Current ASCO and ASRM guidelines recommend that fertility preservation be discussed as early as possible after a cancer diagnosis, before treatment begins. Urgency is greater in these situations because treatment cannot wait.

Elective fertility preservation: People who are not yet ready to have children but want to preserve eggs while they are younger and the eggs are likely to be of higher quality. Timing matters: egg quality and quantity decline with age, and the eggs frozen today reflect the ovarian reserve at that age — not a future one.

A fertility specialist can help you understand your current ovarian reserve, whether egg freezing makes sense given your individual biology, and what a realistic cycle might look like for you.